Previous methods used to encapsulate and provide environmental protection for photovoltaic webs in linear solar collectors have used a variety of polymer-based resins and gels to seal photovoltaic cells and electrical connections from the environment. Such sealing is required to prevent corrosion of components and subsequent performance degradation. Ethyl vinyl acetate (EVA) is commonly used in the encapsulation of flat plate types of photovoltaic receivers. The present invention also uses EVA, but applies it in a new way.
In prior methods of applying EVA, or similar encapsulants, opposing forces are applied to both sides of the solar receiver module, in a vacuum environment. The vacuum is used to evolve dissolved gases and byproducts of the polymer curing process, and may also be used to induce the opposing force required to transport entrapped bubbles. Such a vacuum laminator is similar to a laundry press. The space between opposing plates is placed under vacuum and the polymeric resin is cured using heat, catalysis, or another method. Alternatively, a vacuum chamber is required, containing a means of applying the requisite pressure to the module or receiver.
In U.S. Pat. No. 5,593,532 J. Falk et al. describe a process for manufacturing photovoltaic laminated photovoltaic modules using a vacuum laminator with a heater plate to promote flow of the plastic sealing layers in the encapsulating materials. In U.S. Pat. No. 4,290,838 J. Reavill et al disclose a method for making printed circuits in which a sheet is laminated onto another sheet supported by a substrate with vacuum assistance for drawing air from between sheets to be laminated before they are pressed together. A press fixture is used to apply pressure and to hold the assemblage.
While all of the manufacturing techniques of the prior art have been useful, an object of the invention was to devise a more efficient way of mounting and laminating solar cells in linear solar collectors.